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'''Solenostemon''' is a genus of perennial plants, native to tropical Africa, Asia, Australia, the East Indies, the Malay Archipelago, and the Philippines. They are commonly known as 'Coleus', a name which derives from an earlier classification under the genus name ''Coleus'', species of which are currently included in either ''Solenostemon'' or another genus, ''Plectranthus''.

Contents

Species

Cultivation

Diseases

Propagation

References

Species

Species include:

★ ''Solenostemon autranii'' (Briq.) J. K. Morton

★ ''Solenostemon rotundifolius'' (Poiret) J. K. Morton

★ ''Solenostemon scutellarioides'' (Linnaeus) Codd

★ ''Solenostemon shirensis'' (Gürke) Codd

Cultivation

Many cultivars of the southeast Asian species ''Solenostemon scutellarioides'' have been selected for their colorful variegated leaves, typically with sharp contrast between the colors; the leaves may be green, pink, yellow, maroon, and red (somewhat resembling the unrelated caladium). The plants grow well in moist well-drained soil, and typically grow 0.5-1 m tall, though some may grow as tall as 2 meters. Coleus are typically grown as ornamental plants. They are heat-tolerant, though they do less well in full sun in subtropical areas than in the shade. In cultivation in temperate areas, they are often grown as annuals as they are not hardy and become leggy and unattractive with age. In bright hot areas, the colors of the plant will typically be more intense in shaded areas than in full sun, and the plants will require less water there. Coleus also make low-maintenance houseplants, and can often be propagated by clipping a length of stem just below the leaves and putting the stem in water to root. The plant's flowers grow on a stem above that stem's leaves, and tend to be purple and quite small in comparison to the leaves. The plant is not generally grown for its flowers.

Diseases

One disease that can affect coleus is downy mildew. This mildew appears on the leaves making the plant look dirty because it is brown in color. The organism is called ''Peronospora sp.'' and can also result in curled leaves. The leaves also twist. Sometimes symptoms are not found on leaves which make the disease harder to control.[1] Another disease is Impatiens Necrotic Spot Virus which causes brown or yellow spots on leaves, rings, black or brown stem discoloration, and brown leaf veins. It is a virus that causes plants to die. The disease is spread by an insect called a thrip that develops the disease from the plant of an infected plant and carries it to an uninfected plant. It only takes a few of these insects to infect a whole greenhouse. [2]

Propagation

There are two ways to propagate Coleus. Seeds are inexpensive and easily obtainable. Sprouts can show color in as little as two weeks. Alternatively, cuttings can be taken.

References

★ Annotated Checklist of Cultivated Plants of Hawai‘i: ''Solenostemon''

★ USDA Germplasm Resources Information Network (GRIN): Species Records of ''Solenostemon''